Fraud in Michael Jackson Legal Battle?

04/13/2011.

(TMZ) Katherine Jackson is furious about a declaration filed with the court (the Estate's lawsuit against the Heal the World Foundation) -- purportedly signed by her -- in which she attacks the Executors of the Michael Jackson Estate. TMZ has learned ... Katherine insists she never signed that declaration.

TMZ reported this morning ... a declaration filed in the Estate's lawsuit against the Heal the World Foundation makes shocking allegations against John Branca, calling him a thief.

But Katherine's lawyer, Adam Streisand, tells TMZ, "Mrs. Jackson categorically denies signing any statement to the court that makes accusations against the executors of any wrongdoing with respect to her son or his estate." The plot thickens here